Just sticking my oar in… (boom tishhh).
I use the C2 in the gym at work, a variety of routines, sometimes int’s, some long row.
Intervals to help build my strength and improve technique, as you can focus for short bursts and then recover before your technique falls apart as you tire out.
Long row, up to 10,000m, I like more as challenge and a measure of how fit I am.
Using a HRM is a plus. Sometimes I row to my HR, and not a pace.
As for high resistance? it’s like riding your bike on top gear all the time, you go faster, but it’s harder work. Find a balance that works for you so that you feel most efficient.
At home I have a WaterRower WaterRower. Looks more like a piece of furniture, being made of lovely wood. Is a lot quiter than a C2, and has, apparently, a feel more like a proper boat (according to daughter who is womens captain of her college rowing club). Not so swanky in terms of monitor and data, but a much smoother steadier feel. I have to focus on technique more, as it tires me out quicker than a C2.